Evaluation of the Mechanical Behavior of Mortars Obtained By Geopolymerization of Calcined Clay and Demolition Mortar

Abstract

Geopolymeric mortars were prepared from a mixture of calcined clay powders (from demolition bricks), demolition mortar and a 12 molar alkaline hardening solution of sodium hydroxide. The geopolymeric mortars were compared physically, microstructurally and mechanically with their Portland cement counterparts. The results revealed similar densities between both types of mortars (geopolymeric and ordinary Portland cement). The microstructure was also similar in both mortars, two phases can be clearly identified, the continuous binder phase and the phase of individual fine sand particles dispersed within the continuous cement phase. Regarding the mechanical data, it could be verified that the mixture with 80 Vol.% of fine sand, 10 Vol.% of calcined clay and 10 Vol.% of demolition mortar was the one that showed the best mechanical results, with an average mechanical resistance of 34.5 MPa. However, the highest average mechanical strength value for geopolymeric mortars is below the average mechanical strength value of ordinary Portland cement mortar (50 MPa).